Grounding electrode

[teco]

Hi,
I'd like to post this question again. Looking at table 250.66. Would 3/0 be the largest the grounding electrode conductor would ever need to be using a copper conductor on a parallel sets of service entrance conductors? Example
Eight 500 kcmil per phase. Why?
Thanx
Mark

 

[JohnJ0906]

Hi,
I'd like to post this question again. Looking at table 250.66. Would 3/0 be the largest the grounding electrode would ever need to be using a copper conductor on a parallel sets of service entrance conductors? Example
Eight 500 kcmil per phase. Why?
Thanx
Mark

Yes, 3/0 copper, or 250 kcmil AL.

edit to add: Thats for the Grounding Electrode Conductor. Not for the Grounding Electrode.

 

[teco]

Yes, 3/0 copper, or 250 kcmil AL.

edit to add: Thats for the Grounding Electrode Conductor. Not for the Grounding Electrode.[/B

Thanks for pointing that out.

 

[infinity]

For a GEC #3/0 is the largest required. However 250.66 is also used for sizing the main bonding jumper. For conductors larger than those listed in 250.66 a main bonding jumper would be required to be sized at 12.5% of the phase conductors.

 

[teco]

For a GEC #3/0 is the largest required. However 250.66 is also used for sizing the main bonding jumper. For conductors larger than those listed in 250.66 a main bonding jumper would be required to be sized at 12.5% of the phase conductors.

Thanks very good point.

 

[480sparky]

....Why?....

I think because most of the fault current would flow along the neutral back to the transformer, not into the ground.

 

[teco]

I think because most of the fault current would flow along the neutral back to the transformer, not into the ground.

That's what I was thinking also. Thanks for the opinions.